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T. T. PROSSER. A Steam-Engine.

'l N0. 224,950. Patented F eb.,24, 18806.

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. UNITED 'STATES PATENT' Carica TREAT T. PROSSER, OF CHICAGO, ILLINOIS.

STEAM-ENGINE.

SPECIFICATION forming part of Letters Patent No. 224,950, dated February 24, 1880.

Application led January 27, 1880 To all whom it may. concern Be it known that I, TREAT T. PRossER, of Chicago, in the county of Cook and State of Illinois, have invented a new and useful Improvernent in Steam-Engines, of which the following is a specification.

This invention relates to that class of compound reciprocating steam or other gas-engines in which four single-acting cylinders are arranged radially around a crank-shaft in coincident pairs, which stand at right angles-to each other.

My improvement consists in connecting one pair of pistons to the crank by a single axiallydisposed pitman and the other pair by two pitmen, both attached to the same piston at points equidistant from the center thereof, in consequence of which arrangement the power of the pistons will be transmitted to the crankshaft in such a manner as to equalize the strain on the journals of the latter.

It further consists in the construction and mode of attachment ofthe noddlepins by which the pitmen are respectively connected to the pistons.

It further consists in constructing one of the plates which are used for connecting the several cylinders with a detachable center piece, on removing which the crank-shaft can be taken out, and ready access can be had to the pitmen andtheir adjuncts. i

It further consists in a novel manner of securing the pistons to their stay-rods, admitting of a ready connection or disconnection.

In the annexed drawings, Figure l is a sectional elevation of my improved reciprocating engine. Fig. 2 is a plan view of a portion ot' Fig. 3 isa horizontal section thereof. Figs. 4 to 6 are detail Views, hereinafter lnore particularly referred to.

The same letters of reference are used in all the gures in the designation of identical parts.

The four cylinders A, arranged as best seen in Fig. 3, are bolted to the base-plate B, and are also rigidly connected together on top by a plate, G, of annular form, the central opening of which is covered by a removable center piece, D. The cylinders are closed by heads at their outer ends, but open at their inner ends. The pistons E of each coincident pair of cylinders are permanently secured together by four stay-rods,F, one end of which is screwed into a tap in one of the pistons, while its other end enters aisocket inr the opposite piston, and is secured by a screw-bolt, j', in the manner clearly shown in Fig.. 6. The pistons may thus be readily separated by siniply unscrewing the bolts f.

The crank-shaftGis placedcentrally between the four cylinders, havingabearing in the plate B on one side ofits crank G', and another bearing in the hub ofthe removable center-piece, D, on the other side of the crank. One piston ot' each coincidentpair is connected with the wrist of crank G', and in order to avoid torsional `and canting strains three pitmen, H, I, and l',

are used for this purpose. The pitinanv H oecupies a central position-on the wrist ofthe crank, and is centrally connected to its piston. i

The pitmen I and I are arranged to connect with their piston at points equidistant from the center of the same, and, extending parallelly to the crank, are coupled to the wrist thereoi on opposite sides of pitman H, as best seen in Fig. l.

The pitmen take hold of noddle-pins K and K', secured to the respective pistons. These noddle pins, arranged transversely across the exposed faces of the pistons, are turned so ythat their ends 7c will be segments of a circle, in order that they may lit circular recesses k', formed in the pistons. This will not only center them, but will also give them great steadiness. The pin K, adapted for pitman H, has a single central bearing, while the pin K', intended for pitinen I and I', has two bearings, all as best shown in Fig. 5. The bosses of these pins are snugly fitted to the bottoms ofthe recesses k in the pistons, and are secured by tap-bolts k2, screwed into them through the pistons. 1

Theports of-the four cylinders are covered by steam-chests, and are controlled by four lslide-valves, L, the stems l ofwhich extend through stuffing-boxes in radial directions under a disk, M, secured to the crank-shaft above the center piece, D. The exteriorl end of each valve-stem Z carries a swiveling segment, l', which enters an eccentric groove, m, in the disk M. The eccentricity of this groove m (best seen in Fig. 4) is such as to give the proper throw to the valves, which are operated to open and close IOO the ports' of the several cylinders in regular succession. In this instance thev groove m is circular; but in case a variable valve-motion is desired it Will have the required irregular contour, and the anti-friction rollers Will then be substitutedor the segments. The valvestems project into openings d in the edge of the center piece, so that the latter can be removed Without distnrbin g the valve-stems and adjuncts.

What I claim as my invention,-and desire to secure by Letters Patent, is

l. The compound four-cylinder engine, substantially as described, in which one pair of pistons is connected to a central crank-shaft by a single axially-disposed pitman, and the other pair of pistons by iWo parallel pitmen, both attached to the same piston at points equidistant from the center of the same.

TREAT T. PROSSER.

Witnesses B. E. J. ErLs, JOHN EILs. 

